The goal of this study is to characterize the electrophysiological response and ENaC expression in response to glucocorticoids and mineralocorticoids. The bioelectric consequences of uo- or downregulation of ENaC can be monitored in vivo by measuring nasal transepithelial potential difference. Baseline PD and the inhibition of PD after administration of amiloride reflect the amount of sodium absorption through the apical sodium channel. The cellular expression of ENaC will be demonstrated in nasal epithelia cells harvested by nasal biopsy.